Adrenoreceptors of the guinea-pig urinary bladder.
Br J Pharmacol, 1976/9;58(1):37-41.
PMID: 10034
Impact factor: 9.473
Abstract
1 Adrenaline, noradrenaline and isoprenaline (5 mug/ml) did not affect the resting tone of the isolated urinary bladder of the guinea-pig. 2 The catecholamines (1-2 mug/ml) inhibited neuronally evoked contractions at various stimulation frequencies; the inhibition was maximum at 2 Hz and minimum at 50 Hz. Isoprenaline produced maximum inhibition. 3 Propranolol (0.5 mug/ml) completely blocked the catecholamine-induced inhibition at all the frequencies employed. The concentration-response curves of isoprenaline at 2, 10 and 50 Hz were characteristically shifted by propranolol (50 ng/ml). Phenoxybenzamine (0.2 mug/ml) was totally ineffective. 4 In some experiments adrenaline significantly raised the tone of the bladder exposed to propranolol; this effect could be blocked by phenoxybenzamine. 5 Acetylcholine-induced bladder contractions were inhibited by adrenaline (2 mug/ml); the inhibition was completely blocked by propranolol (0.5 mug/ml). 6 The results indicate the presence of an inhibitory beta-adrenoceptor and suggest the possibility of an excitatory alpha-adrenoceptor in guinea-pig urinary bladder.
MeSH terms
Acetylcholine; Adrenergic beta-Antagonists; Animals; Catecholamines; Electric Stimulation; Epinephrine; Female; Guinea Pigs; In Vitro Techniques; Male; Muscle Contraction; Muscle, Smooth; Receptors, Adrenergic; Urinary Bladder
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